1. Field of the Invention
The present invention relates to a recording tape cassette which accommodates, in a case, a reel on which a recording tape, such as a magnetic tape or the like, is wound, and which is equipped with a lock member for preventing slackening of the reel.
2. Description of the Related Art
Commonly, a magnetic tape cassette which is equipped with a magnetic tape to serve as a recording tape has been widely used with recording/replaying devices such as audio equipment, video equipment and the like. For example, a magnetic tape cassette that is utilized for professional use at broadcasting stations and the like rotatably accommodates a pair of reels in a case which has been structured by joining together an upper case and lower case which are made of synthetic resin. Generally, a magnetic tape is wound on one of the reels and a distal end of this magnetic tape is attached to the other of the reels. The magnetic tape is fed out from the one reel to the other reel, and hence recording of information to the magnetic tape and/or playback of information that has been recorded to the magnetic tape is carried out.
At the middle of a front wall of the case, the magnetic tape is exposed so as to be slideable against a recording/replaying head of a recording/replaying device. When the cassette is not in use (when the cassette is not loaded at a recording/replaying device), the front wall of the case is covered by a cover. This cover is structured to be rotatable upward. When the cassette is to be used (i.e., when the cassette has been loaded at a recording/replaying device), the cover is withdrawn to an upper portion of the case, and the magnetic tape is exposed.
Each of the reels on which the magnetic tape is wound is structured by a lower flange, a hub which is integrally fixed to an upper side of the lower flange, and an upper flange which is attached to an upper side of the hub. A distal end of the magnetic tape is attached to the hub, and the magnetic tape is wound round an outer peripheral surface of the hub. Thus, the magnetic tape that has been wound round at the hub is retained by the upper flange and the lower flange. Further, a hole portion is formed in a lower face of an axial core portion of the hub. When the magnetic tape cassette is inserted at the recording/replaying device, a gear provided in the recording/replaying device (hereafter referred to as a driving gear), which is for transmitting rotary driving force, meshes with a gear that is formed at an inner peripheral face of the hole portion. Thus, with this structure, the pair of reels can be rotated.
As shown in FIG. 4, a gear 58A is formed at a peripheral edge of a lower flange 58, and the gear 58A engages with a lock member 60 which is provided in the case. Consequently, slackening of the magnetic tape that is wound on the reel can be prevented. The lock member 60 is provided with a locking plate 66 and an operation lever 64. The locking plate 66 is substantially J-shaped in plan view and is provided extending from an outer peripheral face of a tubular shaft 62. The operation lever 64 is substantially L-shaped in plan view, and is provided extending from the same outer peripheral face at a side thereof which is substantially 180° opposite from the side thereof at which the locking plate 66 is provided. The tubular shaft 62 is fitted over a shaft 70 which is standingly provided at the lower case. Thus, the tubular shaft 62 is supported so as to be freely rotatable in a horizontal direction.
A torsion spring 68 is fitted over an upper portion of the shaft 70 (a portion which is higher than the tubular shaft 62). One end of the torsion spring 68 is engaged at a spring-retaining portion 65, which is formed at an upper portion of the locking plate 66 and is substantially L-shaped in side view. The other end of the torsion spring 68 is engaged at a shaft 72, which is standingly provided at the lower case. The torsion spring 68 urges the locking plate 66 in a direction of engagement with the gear 58A.
For a magnetic tape cassette that is provided with the lock member 60 having the structure described above, the reels are inserted into the case as follows. Specifically, as shown in FIG. 4, the operation lever 64 of the lock member 60 is rotated in a lock release direction (the direction of arrow P) by hand, and the locking plate 66 is separated from the gear 58A. Then the reel is fed in from above. Thus, when the locking plate 66 is rotated in the lock release direction from the gear 58A and withdrawn from an insertion path (access path) of the reel in this manner, an operation of insertion of the reel into the case is carried out smoothly, without any interference at all with the locking plate 66.
Thereafter, the rotation of the operation lever 64 is released. Consequently, the locking plate 66 is rotated in the direction of engagement with the gear 58A by the urging force of the torsion spring 68, and a distal end of the locking plate 66 engages at the gear 58A. As a result, the reel is locked and slackening of the magnetic tape is prevented.
However, with this method of inserting reels, it is necessary to manually rotate the operation levers 64 of the lock members 60 one by one. Therefore, this insertion operation is extremely troublesome and complicated, and work efficiency is not good.